1. Field of Invention
This invention pertains to a method structure for interconnecting high frequency integrated circuits and more particularly to a method of connecting an integrated circuit to a micro-coaxial substrate.
2. Description of the Prior Art
Conventionally, various integrated circuits disposed on a common circuit board are interconnected by conductive strips which are etched or otherwise deposited on the board. An individual connection is made between each IC terminal and a corresponding strip by wire bonding. A typical example of wire bonding between integrated circuits is shown in U.S. Pat. No. 4,172,261. However it was found that this type of connection is not suitable for high frequency integrated circuits because the wires used in wire bonding have a high parasitic capacitance and inductance and therefore present a high impedance to the signals exchanged between the integrated circuits. One proposed solution was to use optical fibers as the transmission means between integrated circuits. However this approach has two major disadvantages: first the electrical signals must be converted into optical signals, and then back to electrical signals, thus requiring additional components. Second, optical fibers musts be aligned very carefully with the optical signal transmitters or receivers to insure maximum signal transfer therebetween.
One solution which alleviates the problem of high impedance is to provide a coaxial conductor between the IC's. For example, as disclosed in my copending application S.N. 671,276 filed November 14, 1984 entitled Micro-Coaxial Substrate a substrate could be provided which has a plurality of shielded conductors with connecting tabs disposed adjacent to the respective IC's. However if the IC's are connected to the shielded conductors by wire bonding, the unshielded wires of the bond are still long enough to provide an undesirably high impedance. Furthermore these wire bonds are normally made by hand and therefore are expensive, time consuming and unreliable.